U.S. patent number 4,030,290 [Application Number 05/521,264] was granted by the patent office on 1977-06-21 for jet engine thrust reverser.
This patent grant is currently assigned to The Boeing Company. Invention is credited to Claude R. Stachowiak.
United States Patent |
4,030,290 |
Stachowiak |
June 21, 1977 |
Jet engine thrust reverser
Abstract
A thrust reverser suitable for reversing the flow direction of
the fan air of a fan jet engine is disclosed. The thrust reverser
comprises a cascade section and a fan duct blocker section. The
cascade section includes a series of cascade elements mounted in a
side-by-side manner about a portion of the engine nacelle for
rotation through an arc of 90.degree. about longitudinal axes lying
generally parallel to the direction of fan air flow. Each cascade
element includes an inner panel, an outer panel, and a series of
vanes located between the inner and outer panels. Rotation is
between a closed position whereat the inner panel forms a portion
of the fan air duct and the outer panel forms a portion of the
outer surface of the nacelle, and an open position whereat the
vanes define passageways adapted to reverse fan air flow i.e.,
direct fan air flow back toward the front of the engine. The fan
duct blocker section comprises a series of blocker elements linked
together and lying about the inner wall of the fan air duct between
the cascade elements and the aft end of the fan air duct. The
blocker elements are adapted to fan outwardly and form a door that
blocks the fan air duct when the cascade elements are in their open
position.
Inventors: |
Stachowiak; Claude R. (Renton,
WA) |
Assignee: |
The Boeing Company (Seattle,
WA)
|
Family
ID: |
24076058 |
Appl.
No.: |
05/521,264 |
Filed: |
November 6, 1974 |
Current U.S.
Class: |
60/226.2; 60/229;
239/265.27; 60/230; 239/265.33; 251/212 |
Current CPC
Class: |
F02K
1/64 (20130101); Y02T 50/671 (20130101); Y02T
50/60 (20130101) |
Current International
Class: |
F02K
1/00 (20060101); F02K 1/64 (20060101); F02K
003/02 () |
Field of
Search: |
;60/226A,228,229,226R,230,232 ;239/265.33,265.37,265.27
;251/212 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Gordon; Clarence R.
Attorney, Agent or Firm: Christensen, O'Connor, Garrison
& Havelka
Claims
What is claimed is:
1. A thrust reverser for a jet engine comprising a nacelle and a
turbine, said nacelle surrounding said turbine in a manner such
that an air duct is located aft of the turbine, said thrust
reverser comprising:
1. a cascade section including:
a. a plurality of elongated cascade elements mounted in the nacelle
of said jet engine aft of said turbine so as to be rotatably
movable about spaced, generally parallel longitudinal axes that lie
generally parallel to the longitudinal axis of said jet engine
between a closed position whereat said cascade elements form a
portion of the outer wall of said nacelle and a portion of the
outer wall of the aft air duct of said jet engine and an open
position whereat said cascade elements form a passageway between
said aft air duct and the exterior of said nacelle, each of said
cascade elements including a plurality of spaced, curved vanes
lying along their respective longitudinal axes and positioned so as
to direct air from said aft air duct generally toward the air
intake end of said jet engine when said cascade elements are in
their open position, said plurality of cascade elements each
further including inner and outer panels affixed to and mounted on
opposed edges of said spaced, curved vanes such that said plurality
of spaced, curved vanes and said inner and outer panels rotate
together as said cascade elements rotate about said spaced,
generally parallel longitudinal axes, said inner and outer panels
positioned such that said inner panels form said portion of the
outer wall of said air duct and said outer panels form said portion
of the outer wall of said nacelle when said cascade elements are in
their closed positions; and
b. cascade element movement means attached to said cascade elements
for moving said cascade elements between their open and closed
positions; and,
2. an aft air duct blocker section including:
a. A plurality of blocker elements mounted in said aft air duct aft
of said cascade section so as to be movable between a closed
position whereat said blocker elements form a door adapted to block
said aft air duct and an open position whereat said blocker
elements are retracted to a position which allows air to flow
through said aft air duct in a normal manner; and,
b. duct blocker movement means connected to said plurality of
blocker elements for moving said plurality of blocker elements
between their closed and open positions.
2. A thrust reverser for a jet engine as claimed in claim 1,
wherein said inner and outer panels extend outwardly on opposite
sides of said spaced, curved vanes and include undercut regions
along their edges nearest said spaced, curved vanes, said undercut
regions adapted to allow adjacent panels to overlie one another in
a manner such that flush surfaces between said panels exists when
said cascade elements are in their closed positions.
3. A fan air thrust reverser for a fan jet engine comprising a
nacelle and a turbine that includes a high pressure section and a
fan air section, said nacelle surrounding said turbine in a manner
such that an air duct located aft of the fan air section is defined
by the inner wall of said nacelle and the outer fairing of said
high pressure section, said fan air thrust reverser comprising:
1. a cascade section including:
a. a plurality of elongated cascade elements mounted in the nacelle
of said fan jet engine aft of said fan air section so as to be
rotatably movable about spaced, generally parallel longitudinal
axes that lie generally parallel to the longitudinal axis of said
jet engine between a closed position whereat said cascade elements
form a portion of the outer wall of said nacelle and a portion of
the outer wall of the fan air duct of said jet engine and an open
position whereat said cascade elements form a passageway between
said fan air duct and the exterior of said nacelle, each of said
cascade elements including a plurality of spaced, curved vanes
lying along their respective longitudinal axes and positioned so as
to direct fan air from said fan air duct generally toward the air
intake end of said fan jet engine when said cascade elements are in
their open position, said plurality of cascade elements each
further including inner and outer panels affixed to and mounted on
opposed edges of said spaced, curved vanes such that said plurality
of spaced, curved vanes and said inner and outer panels rotate
together as said cascade elements rotate about said spaced,
generally parallel longitudinal axes, said inner and outer panels
positioned such that said inner panels form said portion of the
outer wall of said air duct and said outer panels form said portion
of the outer wall of said nacelle when said cascade elements are in
their closed positions; and,
b. cascade element movement means attached to said cascade elements
for moving said cascade elements between their open and closed
positions; and,
2. a fan air duct blocker section including:
a. a plurality of blocker elements mounted in said fan air duct aft
of said cascade section so as to be movable between a closed
position whereat said blocker elements form a door adapted to block
said fan air duct and an open position whereat said blocker
elements are retracted to a position which allows air to flow
through said fan air duct in a normal manner; and,
b. fan duct blocker movement means connected to said plurality of
blocker elements for moving said plurality of blocker elements
between their closed and open positions.
4. A fan air thrust reverser for a fan jet engine as claimed in
claim 3, wherein said inner and outer panels extend outwardly on
opposite sides of said spaced, curved vanes and include undercut
regions along their edges nearest said spaced, curved vanes, said
undercut regions adapted to allow adjacent panels to overlie one
another in a manner such that flush surfaces between said panels
exists when said cascade elements are in their closed
positions.
5. A fan air thrust reverser for a fan jet engine as claimed in
claim 4, wherein each of said cascade elements includes aligned
first and second shafts, one extending outwardly from either end
along their respective longitudinal axes, said cascade elements
being rotated between their open and closed positions about their
respective first and second shafts.
6. A fan air thrust reverser for a fan jet engine as claimed in
claim 5, wherein said cascade element movement means comprises: a
plurality of link means equal in number to said plurality of
cascade elements, one of said plurality of link means being
attached to one of said first and second shafts of each of said
cascade elements on a one-to-one basis, said link means also being
attached together; and, a driving mechanism connected to said link
means for simultaneously moving said link means and their
associated cascade elements.
7. A fan air thrust reverser for a fan jet engine as claimed in
claim 6, wherein said blocker elements are generally L-shaped in
cross-section and define blocker flanges and fan air duct wall
flanges, said plurality of blocker elements being mounted in said
fan air duct about the outer periphery of said turbine section in a
manner such that said blocker flanges lie in a plane generally
orthogonal to the longitudinal axis defined by said fan jet engine
and said fan air duct wall flanges overlie one another when said
blocker elements are in their closed position, said blocker
elements being mounted so as to be rotatable outwardly from a
position where said fan air duct wall flanges form a portion of the
inner wall of said fan air duct to a position whereat said blocker
flanges block said fan air duct immediately rearwardly of said
cascade section.
8. A fan air thrust reverser for a fan jet engine as claimed in
claim 7, wherein said fan duct blocker movement means
comprises:
a ring surrounding said high pressure section of said fan jet
engine near said blocker elements;
a plurality of links equal in number to said blocker elements, one
link connecting each blocker element to a point in said ring;
and,
driving means connected to said ring so as to rotate said ring, the
rotation of said ring causing said blocker elements to
simultaneously move between their respective open and closed
positions.
9. A fan air thrust reverser for a fan jet engine comprising a
nacelle and a turbine that includes a high pressure section and a
fan air section, said nacelle surrounding said turbine in a manner
such that an air duct located aft of the fan air section is defined
by the inner wall of said nacelle and the outer fairing of said
high pressure section, said fan air thrust reverser comprising:
1. a cascade section including:
a. a plurality of cascade elements mounted in the nacelle of said
fan jet engine aft of said fan air section so as to be movable
between a closed position whereat said cascade elements form a
portion of the outer wall of said nacelle and a portion of the
outer wall of the fan air duct of said fan jet engine and an open
position whereat said cascade elements form a passageway between
said fan air duct and the exterior of said nacelle, each of said
cascade elements including at least one curved vane formed and
mounted so as to direct fan air from said aft fan duct generally
toward the air intake end of said fan jet engine when said cascade
elements are in their open position; and,
b. cascade element movement means attached to said cascade elements
for moving said cascade elements between their open and closed
position; and,
2. a fan duct block section including:
a plurality of blocker elements mounted in said fan air duct aft of
said cascade section so as to be movable between a closed position
whereat said blocker elements form a door adapted to block said fan
air duct and an open position whereat said blocker elements are
retracted to a position which allows fan air to flow through said
fan air duct in a normal manner, said blocker elements being
generally L-shaped in cross-section and defining blocker flanges
and fan air duct wall flanges, said plurality of blocker elements
being mounted in said fan air duct about the periphery of said
turbine section in a manner such that said blocker flanges lie in a
plane generally orthogonal to the longitudinal axis defined by said
jet engine and said fan air duct wall flanges overlie one another
when said blocker elements are in their closed position, said
blocker elements being mounted so as to be rotatable outwardly from
said open position whereat said fan air duct wall flanges form a
portion of the inner wall of said fan air duct to said closed
position whereat said blocker flanges block said fan air duct
immediately rearwardly of said cascade section; and
b. fan duct blocker movement means connected to said plurality of
blocker elements for moving said plurality of blocker elements
between their closed and open positions.
10. A fan air thrust reverser for a fan jet engine as claimed in
claim 9, wherein said fan duct blocker movement means
comprises:
a ring surrounding said high pressure section of said fan jet
engine near said blocker elements;
a plurality of links equal in number to said blocker elements, one
link connecting each blocker element to a point in said ring;
and,
driving means connected to said ring so as to rotate said ring, the
rotation of said ring causing said blocker elements to
simultaneously move between their respective open and closed
positions.
11. A cascade element suitable for use in a jet engine to provide
an exhaust flow path adapted to reverse the direction of airflow,
said cascade element comprising:
a pair of panels spaced from one another; and
a plurality of generally similarly curved vanes, said plurality of
generally similarly curved vanes permanently affixed to said pair
of panels so as to be spaced from one another and lie generally
orthogonal to said panels, said panels and said curved vanes being
spaced such that passageways are defined between said panels and
adjacent vanes, said vanes being curved and positioned such that
air flowing through said passageways is substantially reversed in
its direction of movement.
12. A cascade element as claimed in claim 11, wherein said
plurality of generally similarly curved vanes lie along a common
longitudinal axis; and, wherein said cascade element includes first
and second shafts extending outwardly from either end thereof and
lying along said common longitudinal axis.
13. A cascade element as claimed in claim 12, wherein said panels
extend outwardly in generally parallel planes lying on opposite
sides of said vanes and include undercut regions formed in the
edges thereof nearest said vanes, said undercut regions formed in a
manner such that when two cascade elements are mounted in a
side-by-side manner and suitably positioned, the outwardly
extending panel on one side of one element lies in an undercut
region of the adjacent panel of the other element, and vice versa
with respect to the panels on the other side of said cascade
elements.
14. A blocker door suitable for blocking the fan air duct of a fan
jet engine comprising: a plurality of L-shaped blocker door
elements, each including a blocker flange and a fan air duct wall
flange, rotatably mounted in said fan air duct so as to be movable
between a closed position whereat said blocker flanges block said
fan air duct and an open position whereat said fan air duct wall
flanges overlie one another and allow air to flow through said fan
air duct; and, including fan air duct blocker movement means for
simultaneously moving said blocker door elements between said open
and closed positions.
15. A blocker door as claimed in claim 14, wherein said fan duct
blocker movement means comprises:
a ring surrounding said high pressure section of said fan jet
engine near said blocker door elements;
a plurality of links equal in number to said blocker door elements,
one link connecting each blocker element to a point in said ring;
and,
driving means connected to said ring so as to rotate said ring, the
rotation of said ring causing said blocker door elements to
simultaneously move between their respective open and closed
positions.
Description
BACKGROUND OF THE INVENTION
This invention is directed to jet engines and more particularly to
thrust reversers for jet engines.
Various types of apparatus have been proposed for reversing the
thrust of jet engines. One of the most common devices for reversing
the flow of the fan air of a fan jet engine includes cascades
formed in the engine nacelle and a means for exposing the cascades
when reverse thrust is desired, in combination with a mechanism for
blocking fan air flow in the fan air duct aft of the cascades. In
general, such prior art devices expose the cascades by moving or
retracting a cover usually formed of a heavy ring that surrounds
the nacelle. As the cover is retracted, blocker doors are moved to
a position whereat they block the normal fan air duct outlet. One
of the major disadvantages of this structure is weight, which comes
from the relatively heavy cover utilized to control the exposure of
the open cascades and the heavy mechanism needed to operate the
cover. A further disadvantage relates to the length of the path of
travel traversed by the cover. Specifically, because the
longitudinal distance of this path is substantial, it places
undesirable restrictions on engine design.
Therefore, it is an object of this invention to provide a new and
improved thrust reverser.
It is a further object of this invention to provide a thrust
reverser suitable for reversing the thrust of the fan air of a fan
jet engine.
It is yet another object of this invention to provide a lightweight
thrust reverser suitable for use in a jet engine to reverse fan air
flow.
It is a still further object of this invention to provide a new and
improved thrust reverser that is lightweight and only moves through
a relatively short path of travel.
It is also an object of this invention to provide a new and
improved thrust reverser for use in a jet engine that is radially
located about the engine nacelle in a position that reverses air
flow along the most desirable path.
SUMMARY OF THE INVENTION
In accordance with principles of this invention, a thrust reverser
suitable for reversing the thrust of a jet engine is provided.
Preferably, the invention is used to reverse fan air flow and
comprises a cascade section and a fan duct blocker section. The
cascade section comprises a series of cascade elements mounted in a
side-by-side manner about a portion of the periphery of the engine
nacelle. Each cascade element comprises an inner panel, an outer
panel and a plurality of vanes located between the inner and outer
panels. The cascade elements are adapted to rotate about axes lying
generally parallel to the normal fan air flow path. The inner panel
forms a portion of the fan air duct and the outer panel forms a
portion of the outer surface of the engine nacelle when the
cascades are in a closed position i.e., fan air is flowing in its
normal longitudinal direction through the fan air duct. The cascade
elements are rotatable through 90.degree. to an open position
whereat the vanes are adapted to direct fan air in a reverse
direction i.e., generally back toward the air intake of the
associated jet engine. The blocker section comprises a plurality of
blocker doors located between the cascade section and the aft end
of the fan air duct. In their open position, the blocker doors are
interleaved one upon another and form a portion of the inner wall
of the fan air duct. In their closed position the blocker doors fan
outwardly and block the fan air duct.
In accordance with further principles of this invention, the inner
and outer panels of the cascade elements overlap one another when
the cascade elements are in their closed positions. Further, the
cascade elements are mechanically connected together and operated
by a single driving source.
In accordance with still other principles of this invention, the
blocker doors are linked together and connected to a single driving
source.
In accordance with still further principles of this invention, the
blocker door section includes a ring linked to each blocker door
and a suitable mechanical mechanism adapted to rotate the ring
through an arc adequate to fan the blocker doors outwardly from a
nonblocking position to a fan air duct blocking position.
It will appreciated from the foregoing brief summary that the
invention comprises a thrust reverser suitable for use in reversing
the flow direction of the exhaust of a jet engine. The invention is
particularly suitable for reversing the flow direction of the fan
air of a fan jet engine. The invention overcomes many of the
disadvantages of prior art reversers in that the path of travel or
the flow reversing mechanism is small, particularly when compared
to most prior art devices. Moreover, the invention provides a
reverse structure that is substantially lighter in weight than is
the most commonly used prior art structure wherein a heavy cover is
moved longitudinally to expose cascades.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing objects and many of the attendant advantages of this
invention will become more readily appreciated as the same becomes
better understood by reference to the following detailed
description when taken in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a side view, partially in section, illustrating a fan jet
engine incorporating the present invention;
FIG. 2 is an enlarged view, partially in section, of a preferred
embodiment of the invention;
FIG. 3 is a partial plan view, partially in section, illustrating
the cascade elements of the invention;
FIG. 4 is a perspective view illustrating a single cascade element
formed in accordance with the invention;
FIG. 5 is a partial cross-sectional view illustrating cascade
elements formed in accordance with the invention in their closed
position;
FIG. 6 is a partial cross-sectional view illustrating cascade
elements formed in accordance with the invention in their open
position;
FIG. 7 is a cross-sectional view along line 7--7 of FIG. 2;
FIG. 8 is a partial cross-sectional view illustrating blocker doors
formed in accordance with the invention in their fan duct open
position;
FIG. 9 is a partial cross-sectional view illustrating blocker doors
formed in accordance with the invention in their fan duct closed
position; and
FIG. 10 is a perspective view illustrating a single blocker door
formed in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is an elevational view partially in section illustrating a
preferred embodiment of the invention and comprises a wing 11
supporting a forwardly and downwardly extending strut 13. In a
conventional manner, the strut supports a fan jet engine 15.
The fan jet engine 15 includes a nacelle 17 surrounding the turbine
portions 19 of the fan jet engine. The turbine portions 19 include
a fan air compression section 21 and a high pressure compression
section 23. In a conventional manner, the outer fairing for the
high pressure compression section 23 forms the inner wall 25 of a
fan air duct 27 disposed rearwardly of the fan air compression
section 21. The outer wall 29 of the fan air duct 27 is defined by
the inner surface of the engine nacelle 17.
The thrust reverser of the invention comprises two sections--a
cascade section 31 and a blocker section 33. The cascade section 31
generally comprises a plurality of peripherally located cascade
elements 32 each of which includes a plurality of cascade vanes 39.
The blocker section 33 generally comprises a plurality of blocker
doors adapted to move between a position whereat they form a
portion of the inner wall of the fan air duct 27 and a position
whereat they block the flow of fan air through the normal aft
outlet of the fan air duct 27.
CASCADE SECTION
As indicated above, the cascade section comprises a plurality of
cascade elements 32 located about the periphery of the engine
nacelle, aft of the fan air compression section 21. FIG. 4 is a
perspective view of a single cascade element 32 and illustrates
that each cascade comprises an elongated outer panel 35 and an
elongated inner panel 37. As will be better understood from the
following description, when the cascade elements are in their
"closed" position, the outer panels 35 form a portion of the outer
wall of the nacelle 17 and the inner panels 37 form a portion of
the outer wall of the fan air duct 27. In this regard, the inner
and outer panels are slightly curved so that they conform to the
curved configuration of their associated walls.
The inner and outer panels 35 and 37 are spaced from one another by
a plurality of vanes 39. The vanes 39 are spaced, similarly curved
air flow directing elements that are generally mounted orthogonal
to the inner and outer panels 35 and 37. The spacing between the
vanes define passageways, through which fan air flows during thrust
reversal. The vanes support the inner and outer panels 35 and 37 in
an offset manner whereby each cascade element 32 is generally
Z-shaped in cross-section i.e., one panel projects outwardly in one
direction from one side of the vanes and the other projects
outwardly in the other direction from the opposed side. Support
blocks 41, aligned with the cascade vanes 39, are located at either
end of the overall structure, between the inner and outer panels 35
and 37. Extending longitudinally outwardly, one from each support
block 41, are aligned shafts 43. The shafts 43 define the
longitudinal axis of rotation of the cascade elements 32.
Located along the edges of the inner and outer panels 35 and 37
nearest the vanes 39 are stepped regions 45. The stepped regions
allow adjacent panels to overlap in a manner such that a flush
surface is formed when the cascade elements are in the closed
position hereinafter described.
Preferably, the panels 35 and 37 and the vanes are formed of a
suitable sheet metal, such as an aluminum or titanium alloy.
Moreover, the blocks 41 and shafts 43 are preferably formed of
suitable metals.
As illustrated in FIGS. 1, 3, 5 and 6, a plurality of cascade
elements 32 are mounted in a side-by-side manner in the engine
nacelle 17, aft of the fan air compression section 21. The cascade
elements are mounted such that their longitudinal axes, defined by
their shafts 43, lie essentially parallel to one another, split the
nacelle thickness and lie parallel to the normal direction of fan
air flow. As will be appreciated by those skilled in the art, the
number of cascade elements is determined by the area necessary to
produce adequate thrust reversal without undesirable pressure
buildups occurring. This "area" is defined by the number and size
of the passageways defined by the vanes. In one embodiment of the
invention, 31 cascade elements [3.9 inches wide (average) by 36.0
inches long] were found adequate to provide the necessary area;
however, a greater or lesser number of cascade elements may be
utilized depending upon the actual environment of use of the
invention, and the size of the cascade elements.
The front shafts 43 of the cascade elements are rotatably mounted
in a front ring 47 and the rear shafts are rotatably mounted in an
aft ring 49. The front and rear rings are attached by suitable
attachment means to stringers 48 running through the nacelle, and
to the panels forming the outer wall of the nacelle 17 and the
outer wall of the fan air duct 27. Running between the front and
aft rings 47 and 49 are support beams 51. The support beams 51 are
spaced from one another. In the spaces lie the vane regions of the
cascade elements. The panels of the cascade elements overlie the
support beams. The support beams 51 are I-shaped in cross-section
and have flanged surfaces that diverge slightly outwardly, from
front to rear. At this point it should be noted that the cascade
vanes 39, while being generally similar in curvature, decrease in
size (converge), from front to rear.
The cascade elements are adapted to be rotated through an arc of
approximately 90.degree. by the mechanism hereinafter described.
When in their "closed" position at one end of this arc, as
illustrated in FIG. 5, the outer panels 35 form a portion of the
outer wall of the nacelle 17 and the inner panels 37 form a portion
of the outer wall of the fan air duct 27, adjacent panels
overlapping in the manner previously described. At the other end of
this arc, the cascade elements are in their open position whereat
the inner and outer panels lie substantially orthogonal to the
outer wall of the nacelle, as illustrated in FIG. 6. When in the
open position, the outer surfaces of the cascade panels are pressed
against their adjacent I-beam support elements in a sealing manner.
The apertures defined between the I-beam flanges allow the
rectangular corners of the cascade elements to rotate without
impingement. It should be noted here that the curvature of the
vanes is such that they direct fan air flowing through the
passageways they define back toward the front of the nacelle i.e.,
they reverse the direction of normal fan air flow.
Preferably, all of the cascade elements are simultaneously rotated
by a common driving mechanism. The common driving mechanism
comprises a crank arm 55 extending orthogonally outwardly from one
of the shafts 43 of each element (illustrated as the front shaft).
The crank arms 55 are linked together at their outer ends by
suitable connecting links 57. One crank arm 59 is a bilateral arm
and has its nonlink connected end connected to a ball screw drive
mechanism 61 (FIGS. 5 and 6). As will be understood by those
skilled in the art, the ball screw drive mechanism 61 includes a
threaded shaft 63 adapted to move laterally through a fixed
position housing 61 as a threaded ring mounted in the housing is
rotated by a suitable drive mechanism (not shown). Movement of the
threaded shaft 63 in one direction or the other causes the
bilateral arm 59 to rotate its associated cascade element. Because
the other end of the bilateral arm 59 is connected to the other
cascade elements via the links 57 and crank arms 55, all of the
other cascade elements are also rotated simultaneously.
In summary, the cascade section 31 generally comprises a plurality
of cascade elements located around at least a portion of the
periphery of the engine nacelle 17. The cascade elements are
rotatable about axes which lie generally parallel to the
longitudinal axis of the engine 15. The cascade elements are formed
such that when closed they form portions of the outer wall of the
nacelle and the outer wall of the fan air duct. When open, the
cascade elements provide pathways through which fan air can flow.
Vane elements define the pathways and are formed in a manner that
reverses the direction of fan air flow. Thus, a thrust reverser is
formed when the cascade elements are open. It will be appreciated
that because the cascade elements are formed of relatively
lightweight sheet material, their overall weight is substantially
less than prior art devices which include a heavy housing that must
be moved longitudinally to expose cascades. Moreover, the path of
travel of the cascade elements is relatively short when compared to
prior art structures.
BLOCKER SECTION
The blocker section 33 generally comprises a plurality of blocker
doors 71 that fan outwardly from a stowed position whereat they
form a portion of the inner wall of the fan air duct to a position
whereat they block the fan air duct aft of the cascade elements.
FIG. 10 is a perspective view of a single blocker door 71. The
blocker doors 71 are generally L-shaped in cross-section. For
purposes of discussion, one of the flanges of the L-shaped section
73 is defined as a blocker flange and the other flange is defined
as a fan air duct wall flange 75. The two flanges are joined
together at a common edge 79. The blocker flange 73 defines two
curved edges 77 and 79 that diverge with respect to one another,
even though the curves generally extend in the same direction. The
narrower end 74 of the blocker flange is defined as the rotation
end. The outer end 81 has a radius of curvature equal to the radius
of curvature of the outer wall of the fan air duct, as will be
better understood from the following description. The rotation end
74 of the blocker flange 73 includes an aperture 78 in the corner
remote from where it joins the fan air duct wall flange 75.
The fan air duct wall flange 75 includes three regions 85, 87 and
89 separated by steps 86 and 88. Each of the regions is
substantially the same in length, extending from one end 90 to the
other end 92 thereof. The purpose of the stepped regions is to
allow the blocker doors to overlap when the blocker doors are in
their stowed position. In this manner the stowed configuration
forms a relatively smooth fan air duct wall in the region of the
blocker section, as hereinafter described.
As best illustrated in FIG. 7, two arms 91 and 93 are affixed to,
and extend inwardly from, the inner surface of the fan air duct
wall flange 75. One arm 91 is near the common edge 79 and merely
defines a yoke having aligned apertures 92 in the legs of the yoke.
The other arm is near the other edge of the fan air duct wall
flange 75 and extends outwardly as well as inwardly. The outer tip
of the latter arm also defines a yoke having aligned apertures 94
in its legs. The apertures 92 and 94 in both yokes lie along a
common axis 83. The common axis, as will be better understood from
the following description, is the axis of rotation of the
associated blocker door 71.
A suitable support structure 96 supports a support channel 98 about
the high pressure section of the jet engine. The support channel 98
is positioned beneath the region where the blocker doors 71 form a
portion of the inner wall of the fan air pg,12 duct. The support
channel 98 supports aligned pairs of T-shaped arms, one pair
associated with each blocker door 71. The legs of the T-shaped arms
extend outwardly and include apertures having a common axis. The
spacing of the T-shaped arms is the same as the spacing between the
yokes defined by the two arms 91 and 93 extending inwardly from the
fan air duct wall flanges 75. When the blocker doors are in their
operative positions, the yokes surround the outwardly extending
legs of the T-shaped arms and pins 100 rotatably afix these members
together.
As noted above, the blocker doors 71 are mounted so that they lie
between the aft end of the cascade elements 31 and the aft end of
the nacelle 17. The blocker doors are mounted such that the blocker
flanges 73 lie generally orthogonal to the main longitudinal axis
of the engine 15. In addition, the blocker doors are mounted such
that the fan air duct wall flanges of adjacent blocker doors 71
overlap one another when the blocker doors are in their stowed
positions. The blocker doors are rotatable through an arc of
approximately 90.degree. from a stowed position whereat the fan
duct doors 75 overlap one another to a blocking position whereat
the blocker flanges 73 lie side-by-side and prevent flow through
the fan air duct 27, aft of the cascade elements 31. Rotation is
about the axis 83 along which the pins 100 lie. It will be
appreciated that the blocker doors, in essence, "fan" outwardly as
they are moved from their stowed position to their blocking
position.
Rotation of the blocker doors is accomplished by a linking
mechanism connected to the apertures 78 formed in the blocker
flanges 73. The linking mechanism is best illustrated in FIGS. 8
and 9 and comprises a plurality of links 95 one associated with
each blocker door 71. The links extend between their associated
apertures 78 and spaced points on a ring 97 which surrounds the
high pressure section 23 of the engine 15. The ring 97 is in turn
connected to a ball screw mechanism 99 (FIGS. 2 and 7). The ball
screw mechanism 99 comprises a threaded shaft 101 and a suitable
rotating mechanism 103. When the rotating mechanism is operated by
a suitable drive mechanism (not illustrated), longitudinal movement
of the threaded shaft 101 occurs. This longitudinal movement, in
turn, causes rotation of the ring 97. Rotation of the ring 97 in
one direction causes the blocker doors to move outwardly about
their axes of rotation to a position whereat they block the fan
duct channel 27. Rotation in the opposite direction returns the
blocker doors to a position whereat they form a portion of the
inner wall of the fan duct 27. These "stowed" and "deployed"
positions are illustrated in FIGS. 8 and 9, respectively. Because
all of the blocker doors are all linked to a common rotatable ring,
they are simultaneously moved between their blocking and
nonblocking positions. Obviously, the movement of the cascade
elements between their closed and open positions and the blocker
doors between stowed and deployed position is preferably done
simultaneously when thrust reversal is desired.
It will be appreciated from the foregoing description that the
instant invention comprises a new and improved thrust reverser
suitable for use with jet engines and, in particular, fan jet
engines. An uncomplicated mechanism is provided for deflecting the
fan air rearwardly from the fan air duct. In addition, an
uncomplicated mechanism is provided for blocking the fan air duct
during thrust reversal. Because the path of travel of both
mechanisms is relatively short, large and complex moving mechanisms
are not required.
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